1. Field of the Invention
The present invention is broadly concerned with improved apparatus and methods for the fabrication of poured concrete sandwich walls having a central, thermally insulating sheet or section. More particularly, the invention is concerned with insert assemblies which are preferably prefabricated and field-modified as needed, and are then positioned between conventional concrete form panels. The insert assemblies include a central insulative sheet with a pair of reinforcing bar assemblies adjacent each face of the sheet and operably coupled to the latter by means of cross-connectors.
2. Description of the Prior Art
Poured concrete wall structures may be equipped with one or more internal, upright sheets or bodies of thermal insulation, typically made up of a synthetic resin foam material. Such wall structures are known in the art as sandwich walls, referring to the fact that the insulating foam is sandwiched between outer concrete layers. The construction of concrete sandwich walls generally involves placing the insulative foam between opposed concrete form panels together with reinforcing bars on opposite sides of the foam, and pouring concrete into the form.
However, there are a number of problems associated with the construction of concrete sandwich walls. The insulating foam has very little structural rigidity, and can easily become warped or broken by the concrete as it is poured. Accordingly, it is the practice to carefully pour the concrete on both sides of the insulating foam in an even fashion, in an effort to avoid overloading and harming the foam material. Moreover, while the reinforcing bars are placed precisely relative to the foam material prior to the pour, the bars tend to float or shift during the pour, often leading to foam movement or damage. In some cases spoked “wheels” are positioned around the reinforcing bars during setup, in order to partially secure the bars in place. But if the bars shift during the pour, the spokes can penetrate the foam, degrading the entire sandwich wall.
The assembly of the insulating foam/reinforcing bars, with or without positioning wheels, is carried out at the construction site with the form panels. This is a time-consuming, labor-intensive undertaking normally extending over several days, which necessarily ties up the form panels and ancillary forming equipment resulting in lost opportunities to do other construction jobs.
U.S. Pat. Nos. 4,805,366, 4,829,733 and 5,671,574 describe the construction of concrete sandwich walls. The primary function of the forming apparatus of these patents is to center the insulating foam during the pour. Reinforcing bar assemblies are utilized, but the assembly bars are simply tied together and also tied to transverse form ties, without any direct connection to the foam. As such, the bar assemblies can shift during a pour.
There is accordingly a need in the art for improved apparatus and methods for the construction of concrete sandwich walls, which minimize or eliminate the problems inherent in prior art practices.